This invention relates to a an aircraft passenger seat assembly which includes an emergency oxygen system, and the subcombination of a supplemental emergency oxygen system for aircraft passenger seats. Such an emergency system is required equipment for all high-altitude commercial aircraft. The system is in a non-activated state so long as the pressurization equipment of the aircraft is functioning properly, and the cabin altitude is maintained at the proper level. Upon decompression, a compartment door opens, exposing emergency oxygen masks which are taken by the passengers and placed over the mouth and nose. Pulling the mask to the face activates the firing pin of a chemical reaction oxygen generating canister, causing oxygen to flow to the mask. Most systems have the masks stored in an overhead compartment behind a normally-locked door. Decompression causes the door to unlock and the masks fall free into a position generally in front of and within reach of the passengers.
The invention disclosed and claimed in this application has particular application for use in aircraft seats intended for DC-10 aircraft. The masks are stored in a compartment in the upper back of the passenger seat above the seat-back tray table. Generally, one compartment is provided for every three passengers, with three masks being positioned in each compartment.
U.S. Pat. No. 4,609,166 discloses an emergency oxygen system for aircraft wherein the oxygen canister is mounted in the seat frame of the seat in front of the passengers who will use the masks to which the canister supplies oxygen. The masks are positioned in normally-locked compartments in the seat back. A cable is loaded by a powerful spring and locked in the loaded position by a locking pin. When one of the masks is pulled free of the compartment, the locking pin is pulled from a releasing mechanism, releasing the spring, which jerks the cable connected to the firing pin of the oxygen canister, which in turn pulls a locking pin free and releases the firing pin, thus starting the reaction which generates oxygen.
The mechanism disclosed in the '166 Patent relies on the power stored in the spring to pull the locking pin out of the firing pin. Three separate connected movements are required--the pull of the tether which pulls the locking pin from the release mechanism in the compartment, the release of the spring which jerks the cable, and the pull of the locking pin from the firing pin of the oxygen canister. Any malfunction in the spring, for example, foreign matter trapped in the spring or wedged against the release mechanism, could cause the device to malfunction. Three separate movements must be performed correctly.
The invention disclosed in this application simplifies the procedure by directly connecting the pull of the tether which release the mask to the pull of the locking pin from the firing pin of the oxygen canister.